Motorized traverse rod operator



July 2, 1963 H. STEINGASS ETAL 3,

MOTORIZED TRAVERSE ROD OPERATOR 3 Sheets-Sheet 1 Filed April 10, 1961 FIG.2

FIG. I

y 1963 H. STEINGASS ETAL 3,096,078

MOTORIZED TRAVERSE ROD OPERATOR 3 SheetsSheet 2 Filed April 10, 1961 July 1963 H. STEINGASS ETAL 3,096,078

MOTORIZED TRAVERSE ROD OPERATOR v 5 Sheets-Sheet 3 Filed April 10, 1961 FIG. 10

FIG. 7

ilnired rates Fatent 343963723 MQTGHZED TRAVERSE RQD OEPERATQR Hermann Steiugass and Ilare L. Milton, In, Baltimore,

Md, assigners to Eastern Products Qorporation, Baltimore, Md, a corporation of Maryiand Filed Apr. 10, 1961, Ser. No. 161,985 19 Claims. (fl. 254175.3)

The present invention relates to drapery and curtain hardware and more particularly to a motorized traverse rod operator.

In providing powered operators for drapery and ourtain rods, various problems have been encountered which have required the use of complicated and expensive constructions to afford satisfactory operation. One such problem has been to obtain efiicient transmission of motor torque to the drapery cord to provide a traversing force on the drapes. A related problem has been to effect such transmission of torque in a manner minimizing torque requirements.

Another problem has arisen in connection with the tendency for drapery cords to become increasingly permanently stretched as a result of operating tension over repeated cycles of operation.

These and other problems have limited the usefulness and applicability of previous powered drapery operators.

The principal object of the present invention has been to provide a novel and improved powered operator for drapery and curtain rods and the lflre.

More particularly, it has been an object of the invention to provide a novel and improved powered operator for drapery and curtain rods and the like which is simple and economical in construction, easy to install and reliable in operation.

Another object of the invention has been the provision of an operator of the above type which maintains auto maticaliy proper cord tension despite substantial elongation of the operating cord and which can easily be adjusted to accommodate cord elongation greater than that which can be accommodated automatically.

A further object of the invention has been the provision of such an operator which permits immediate manual operation of the operating cord in the event or" power failure or unit failure.

Still another object of the invention has been the provision of such an operator which is easy to install.

A still further object of the invention has been the provision of such an operator which maintains a slight fixed tension on the slack leg of the operating cord while torque is being transmitted to the working or tensioned leg.

Other and further objects, features and advantages of the invention will appear more fully from the following description taken in connection with the appended drawings, in which:

FIG. 1 is a front elevational view of one form of motorized traverse rod operator embodying the invention with the front cover removed and with part of the housing broken away;

FIG. 2 is a side elevational view of the operator of FIG. 1 with part of the housing broken away;

FIG. 3 is a top plan view of the operator of FIG. 1 with part of the top broken away;

FIG. 4 is a fragmentary front elevational view showing the operator of FIG. 1 in rest position with a drapery operating cord threaded therethrough;

FIG. 5 is a view similar to FIG. 4 but with operating torque being supplied to the right-hand cord leg;

FIG. 6 is a view similar to FIGS. 4 and 5 but with operating torque supplied to the left-hand cord leg;

FIG. 7 is a longitudinal sectional view taken along the line 7-7 of FIG. 1;

ice

FlG. 8 is an enlarged front elevational view of the cord sheave of FIG. 1;

H6. 8A is a side elevational view of the cord sheave of FIG. 8;

FIG. 9 is a front elevational view illustrating a mounting bracket for use with the operator of the invention; and

FIG. 10 is a fragmentary sectional view illustrating a modified form of operator construction in accordance with the invention.

Referring now to the drawings, the operator of the invention comprises a generally rectangular housing 20 having atop 22, a bottom 23, sides 2 and 25, and a front 26. The housing 20 may be made of any suitable material but is preferably molded plastic. Approximately the upper half of the front 26 is indented to provide a recess 27 extending across the width of the housing, as best shown in FIG. 1. Directly behind the rear wall of the recess 27 is a metal plate 28 forming the principal structural element. The plate 28 has a rearwardly extending top 28' and a rearwardly extending bottom 23". A downrwardly extending flange 2$A extends from the end of bottom 28", the flange 28A terminating in a horizontal flange 288 which rests on bottom 23- of housing 20.

The unit is provided with a removable cover 29, which is omitted from PEG. 1 to better illustrate the mechanism of the invention. The cover 29 has a front 30 adapted to close the recess 27 and a top 31. The top 31 is provided with a rearwardly extending tab 32 which has a finger 33 adapted to engage a recess 34 in the top 22 to releasably hold the cover 29 in place on the housing 29'.

The bottom of front 3% of cover 29 has :a rearwardly extending flange 36 ending in a downwardly extending (linger 37 adapted to enter a slot 38 in front 26 to hold cover 29.

The top 31 of cover 29 is provided with openings 39 which accommodate drapery operating cord legs 49' and 41, as shown in FIGS. 4-6.

A cord sheave 42. is mounted on a shaft 43 carried for rotation in a suitable bearing 44 which is mounted in an aperture in plate 28. The bearing 44 is preferably a ball hearing. The shaft 43 extends into a gear box 45 mounted on the inner side of the plate 28. Gear box 45 provides a direct mechanical connection with an electric motor 46 mounted in the housing 20 and supported on the plate 28.

The gear box 45 contains gears which have ratios selected to drop the motor operating speed to a relatively slow sheave speed, e. g., a speed reduction of 25.8 to 1. A typical motor speed might be 3150 rpm. and a typical cord sheave speed might be 122 rpm, both at no load. The gearing Within the box 45 is preferably formed by spur gears which permit manual rotation of the sheave 42. The use of a worm in the gear box is undesirable since it would prevent such manual rotation unless a clutch mechanism is provided between the sheave and the worm. The motor 46 is preferably an alternating current fractional horsepower motor, and should be of a type which can be stalled completely without causing an undue current drain. A suitable motor might be a reversible, capacitor-start, single phase induction motor designed to withstand stall in either direction of rotation. Other typical motor characteristics might be a cold starting torque of 11 inch pounds per minute and an output torque of 7.8 inch pounds per minute at 97 rpm. A motor of this type is desirable since, when the master slide reaches the end of its travel, motion of the cord must stop without undue force being exerted on the drapery rod. If a clutch is used between the motor and the sheave stalling of the motor is not needed and a series motor or other type of motor may be used. The clutch may be arranged to operate an electrical switch to shut oil the motor when motion of the master slide stops.

Idler pulleys 47 and 43 are mounted on shafts 49 and respectively; The shafts 49 and 54 are journaled for rotation in ball bearings mounted in plate 23. If desired, the shafts 49 and 58 may be stationary and the pulleys 47 and 48 may be rotatably carried thereon by ball bearings.

The shafts 49 and 543 are disposed upwardly of and on respective sides of shaft 43, but are spaced relatively close to shaft 43, so that when the drapery operating cord is threaded over pulleys 47 and 45 and around sheave 42 the operating cord will be held close to sheave 42 and in contact with as great an arc as possible of the sheave 42. The spacing of these shafts is as close together as possible, consistent with easy threading of the drapery cord. The shafts 43, 49 and 5%? are parallel to each other.

As is best shown in FIGS. 8 and 8A, cord sheave 42 is provided with spaced ribs 53 extending inwardly from one face thereof and spaced ribs 5 extending inwardly from the opposite face thereof, the ribs 54 being staggered with respect to the ribs 53 so that the cord follows a sinuous path about the sheave 42. This arrangement afiords a substantial increase in traction over what could be obtained with a plain sheave and is not subject to the Wear which would be experienced by a rubber coating or the like on the sheave.

Adjacent each side of the housing 29 is a vertical guide or housing which may be integral with or affixed to the inner surface of the front 26. These guides, which may be rectangular in cross section, are shown at 55 and 56. Within each of the housings 55 and 56 there is provided an inner slide, best shown at 57 in FIG. 7 and at 57 and 58 in FIG. 1. The inner slides 57 and 58 are closed at the bottom and front and rear walls which slidably contact the front and rear walls of the housings 55 and 56, respectively. The housing 55 is provided with a laterally extending centrally located pin 59 just below the top. A centrally located pin 61 projects from the bottom of slide 57.

One end of a coil compression spring 61 is hooked over pin 59 and the other end of spring 61 rests against the closed bottom of slide 57. The pins are provided to retain the spring in position. The arrangement is such that, as the slide 57 is pulled upwardly in a direction out of housing 55, spring 61 becomes compressed and hence exerts a force on the bottom of slide 57 tending to force slide 57 back into housing 55. The rear wall 62 of slide 57 extends upwardly and is provided with a top 63 and a front extension 63. A shaft 64- is mounted in walls 62 and 63. The wall 63' is separated from the main portion of slide 57 by a cord threading space 63" (-FIG. 7). Shoulders on the slide 57 engage housing 55 and hence limit downward motion of slide 57 into housing 55 under action of spring 61. Shaft 6 carries an idler pulley 65.

Since the pulley 65 is supported on the slide 57, this pulley is constantly urged downwardly by the spring 61. A similar pulley mounted on shaft 66 is associated with housing 56 and slide 58.

An arm 67 is pivotally attached adjacent one end thereof to shaft 64. The other end of arm 67 has a hooklike shape adapted to engage and be releasably retained by a projection 68 extending from the front wall of slide 57. With arm 67 engaged with projection 68 as shown in FIG. 7, both ends of shaft 64 (and hence pulley 65) are supported on the slide 57 despite the cord space 63" separating the upper and lower portions of the front wall of slide 57 When it is desired to thread a cord around pulley 64, arm 67 is disengaged from projection 68 and pivoted so as to expose space 63". A similar arm 69 is provided for the pulley carried on shaft 66.

The top 63 of pulley supporting slide 57 is fiat and is adapted to engage a stop arm 71 projecting outwardly from front wall 26 into recess 27. Contact between top 63 and stop 71 serves to limit upward travel of slide 57 and pulley 65. Pulley supporting slide 53 has a fiat top .72 adapted to engage a stop arm 73 projecting outwardly from wall 26 and which similarly serves to limit upward travel of slide 58 and the pulley carried therein.

The housing 2.9 may conveniently be mounted on a Wall, window frame or other convenient place adjacent the normal path of the drapery operating cord. For such mounting there may be provided a flat metal plate 74 (FIGS. 2 and 9) which corresponds in size and shape to the open back of housing Zil. The plate 74 has four spaced elongated slots 75, 76, 77 and 78 each of which accommodates a wood screw or other fastening device to attach the plate 74 to the desired Wall or other surface. Initially, the screws or other fastening devices should be located near the bottoms of the slots to permit the plate later to be lowered. A hole in a forwardly extending flange 7 9 of plate 74 accommodates 'a screw 3! which acts in a threaded hole in flange 233 for releasable attachmerit of the housing 2% to plate 74. Elongated slots 81 and 82 in forwardly offset portion 74' of plate 74 accommodate hooklike extremities of top 23' of plate 28 to also provide releasable attachment of housing 20 to plate 74.

An electrical switch 33 is mounted in an aperture in front 26 of housing 20. The switch 83 should be of a type which is normally in a neutral position but which, while pushed in one direction, completes an operating circuit for motor 46 in one direction, and, whilepushed in the other direction, completes a reverse direction operating circuit for motor 46.

The operator of the invention should be used with an endless drapery cord. Such cords commonly extend downwardly from one end of the drapery rod in a long loop, and pulling one leg of the loop causes the master slide :or master slides to move in drapery opening direction, while pulling the other leg of the loop causes the master slide or slides to move in drapery closing direction. A plate 48A pivoted about a pin 45B projecting outwardly from front wall 26 is adapted to shield the front of pulleys 47 and 43 and prevent the cord from accidentally becoming unthreaded. A projecting portion 47A of wall 26 serves a similar function at the backs of pulleys 47 and 48. In downward position, plate 48A rests on a pin 48C. For purposes of threading the plate 48A is pivoted about pin 48B to expose the pulleys 47 and. 48.

Referring now to FIG. 4, reference numerals 40 and 41 apply to the respective legs of an endless drapery operating cord. The cord is threaded through the operator by passing under and around the left tensioning pulley, i.e., the one carried on shaft 66, over and around idler pulley 43, under and around sheave 42, over and around idler pulley 47, and under and around the right tensioning pulley 65. The tensioning pulleys are shown in FIG. 4 in typical positions for the operator at rest.

Tension is exerted on cord leg 41 (FIG. 5) by rotating cord sheave 42 in a clockwise direction. The tension on cord leg 41 is caused by the torque exerted by motor 46 through cord sheave 42 and the opposition to motion by the friction and drag of the moving parts and especially the weight of the draperies, which'are moved as cord 41 moves downwardly. As sheave 42 starts to rotate in a clockwise direction (FIG. 5), the slack in cord leg 41 is taken up by pulling the right tensioning pulley 65 upwardly against the action of its spring 61. The pulley 65 moves upwardly until top 74 of slide 57 contacts stop 71. Thereafter continued motion of sheave 42 results in actual downward motion of leg 41, as shown by arrow 84.

With tension on leg 4-1, leg 49 becomes the slack leg and will move upwardly, as shown by the arrow 85, but lWll]. not be subjected to the same force as the leg 41, as the leg 40 will only be following themotion of its master slide. However, leg 46 is not allowed to become loose since it is maintained under slight tension through the spring pressure tending to pull the left side tensioning.

pulley downwardly. Hence, the left pulley side tensio shown in FIG. 5, where the leg 4% is held under a balanced force condition.

When sheave 42 stops rotating, there will be a tendency for pulley 65 to be pulled down slightly under the action of spring 61 to a position such as shown in FIG. 4. The pulley on shaft 66 will tend to remain in about the same position in FIG. 4 as in FIG. 5.

When cord sheave 42 is rotated in a counterclockwise direction (FIG. 6), cord leg 49 becomes the tensioned leg, and the left side tensioning pulley will be pulled up- Wardly against spring pressure until top 72 of slide 53 contacts stop 73. As leg 4-1 tends to become slack, spring 61 will pull right side pulley 65 downwardly until pulley 65 assumes a balanced force position, as shown in FIG. 6.

Over repeated cycles of service, the cord will be come increasingly permanently length ned, putting more slackin the slack cord leg. However, this slack will be accommodated automatically by the slack leg tensioning pulley (left in FIG. 5 and right in FIG. 6) assuming a lower position under its spring urging.

Should the cord become so lengthened that the automatic tensioning is insufficient to take up the slack, then the slack tensioning pulley will be in its bottom position, as in FIG. 1. This excess slack can be accommodated and the automatic tensioning restored to functioning condition by removing housing 283 from plate 74 and moving plate '74 downwardly with respect to its mounting screws. The elongated slots 75- 78 facilitate such downward adjustment. Should the slack take-up afforded by tie automatic tensioning and by repositioning of mounting plate 74 be exhausted, additional slack may be taken up at the master slides. In a typical installation, the automatic slack take-up might handle 4 inches of slack, while the elongated slots in the plate 74 might take up 5 inches of slack. It is desirable that the switch 83 automatically return to neutral position when released. It is also desirable that a thermal cut out device he provided to prevent motor operation if the motor becomes overheated, which may occur if the motor is operated excessively, :which may be expected with children.

A remote control switch for operating the motor 4-6 may be provided in addition to or in lieu of the switch 83. It may in some cases be desirable to mount gear box 45 at the rear of the housing, as in FIG. 10, and the cord sheave shaft 43 may extend into an elongated socket 43 extending from the gear box 45, The shaft 2-3 is slidable axially in the socket 43. The shaft 43 may be splined so as to rotate with the socket 43'.

While the invention has been described in connection with specific embodiments thereof and in a specific use, various modifications thereof will occur to those skilled in the art without departing from the scope of the invention as set forth in the appended claims.

What is claimed is:

1. A powered operator for operating draperies and the hke by imparting axial motion to an operating cord, comprising a reversible motor, a cord sheave, mechanical means intercoupling said motor and said sheave for rotating said sheave when said motor is powered, a pair of tensioning pulleys, mounting means for said tensioning pulleys arranged to permit translational motion of said tensioning pulleys, said sheave and said pulleys being arranged so that an operating cord may be threaded around .one tensioning pulley, thence around said sheave and thence around the other tensioning pulley, whereby rotation of said sheave in one direction causes said cord to advance axially in one direction and rotation of said sheave in the other direction causes said cord to advance axially in the other direction, biasing means operatively .coupled to said tensioning pulleys and constantly urging said tensioning'puileys to move in a direction to maintain said cord in tension, and a stop disposed in the path of motion of each of said tensioning pulleys and arranged r d to limit motion of said tensioning pulleys in a direction opposite to the direction of motion resulting from urging of said biasing means.

2. A powered operator for operating draperies and the like by imparting axial motion to an operating cord, comprising a reversible electric motor, a cord sheave, mechanical means intercoupllng said motor and said sheave for rotating said sheave when said motor is powered, a pair of rotatably mounted idler pulleys, a pair of tensioning pulleys, mounting means for said tensioning pulleys arranged to permit translational motion of said tensioning pulleys, said sheave and said pulleys being arranged so that an operating cord may be threaded around each of said pulleys and said sheaves, said cord being threaded around one tensioning pulley before being threaded around said sheave and being threaded around the other tensioning pulley after being threaded around said sheave, whereby rotation of said sheave in one direction causes said cord to advance axially in one direction and rotation of said sheave in the other direction causes said cord to advance axially in the other direction, spring means operatively coupled to said tensioning pulleys and urging said tensioning pulleys to move in a direction to maintain said cord in tension, and a stop disposed in the path of motion of each of said tensioning pulleys and being arranged to limit motion of said tensioning pulleys in a direction opposite to the direction of motion resulting from urging of said spring means.

3. A powered operator for operating draperies and the like by imparting axial motion to an operating cord, comprising a reversible electric motor, a cord sheave, mechanical means intercoupling said motor and said sheave for rotating said sheave when said motor is powered, a pair of rotatably mounted idler pulleys, a pair of tensioning pulleys, mounting means for said tensioning pulleys arranged to permit longitudinal motion of said tensioning pulleys, said sheave and said pulleys being arranged so that an operating cord may be threaded around said pulleys and said sheave, said cord being threaded about one idler pulley and one tensioning pulley before passing around said sheave and being threaded about the other idler pulley and the other tensioning pulley after passing around said sheave, whereby rotation of said sheave in one direction causes said cord to advance axially in one direction and rotation of said sheave in the other direction causes said cord to advance axially in the other direction, spring means operatively coupled to said tensioning pulleys and urging said tensioning pulleys to move longitudinally in a direction to maintain said cord in tension, and a stop disposed in the longitudinal path of each of said tensioning pulleys and arranged to limit longitudinal motion of said tensioning pulleys in a direction opposite to the direction of motion resulting from urging of said spring means, the strength of said spring means being suilicient so that the slack leg of said operating cord is maintained under spring tension but being insufiicient to prevent the tensioned leg of said operating cord from pulling the adjacent tensioning pulley against its stop.

' 4. A powered operator for operating draperies and the like by imparting axial motion to an operating cord, comprising a reversible electric motor, a cord sheave, mechan 'ical means intercoupling said motor and said sheave for rotating said sheave when said motor is powered, a pair of idler pulleys rotatably mounted adjacent said sheave, a pair of tensioning pulleys, mounting means for said tensioning pulleys arranged to permit longitudinal motion of said tensioning pulleys, said sheave and said pulleys being arranged so that an operating cord may be threaded around one tensioning pulley, thence around one idler pulley, thence around said sheave,rthence around the other idler pulley and thence around the other tensioning pulley, whereby rotation of said sheave in one direction causes said cord to advance axially in one direction and rotation of said sheave in the other direction causes said cord to advance axially in the other direction, spring direction to maintain said cord in tension, and a stop disposed in the longitudinal path of each of said tensioning pulleys and arranged to limit longitudinal motion of said tensioning pulleys in a direction opposite to the direction of motion resulting from urging of said spring means, the strength of said spring means being suificient so that the slack leg of said operating cord is maintained under spring tension but being insufiicient to prevent the tensioned leg of said operating cord from pulling the adjacent tensioning pulley against its stop;

5. A powered operator as set forth in claim 4 in which said idler pulleys lie in the same plane as said sheave and in which there are provided first and second guard means disposed on opposite sides of said idler pulleys and said sheave to prevent accidental unthreading of said cord, one of said guard means being pivotally mounted and being arranged when pivoted to expose said'idler pulleys and said sheave to permit threading of said cord. v 6. A powered operator for operating draperies and the like by imparting axial motion to an operating cord, comprising a housing having a cover with openings adapted to accommodate respective legs of an operating cord, a reversible electric motor mounted in said housing, a cord sheave rotatably mounted in said housing, gear means intercoupling said motor and said sheave for rotating the latter when said motor is powered, a pair of idler pulleys each rotatably mounted in said housing about axes parallel to the axis of said sheave, a pair of tensioning pulleys each rotatably mounted in said housing, individual mounting means for each of said tensioning pulleys arranged to permit longitudinal motion of said tensioning pulleys toward and away from a respective one of said openings, each of said mounting means comprising a spring arranged to urge the corresponding tensioning pulley away from the corresponding opening, and a pair of stop arms each disposed in the longitudinal path of a respective one of said tensioning pulleys and arranged to limit longitudinal motion of the corresponding tensioning pulley toward the corresponding opening, said pulleys and said sheave being arranged so that said cord entering one of said openings may be threaded first around the corresponding tensioning pulley, thence around one of said idler pulleys, thence around said sheave, thence around the other idler pulley, thence around the other tensioning pulley and through the other opening.

7. A powered operator for operating draperies and the like by imparting axial motion to an operating cord, comprising a housing having a removable cover with openings adapted to accommodate respective legs of an operating cord, a reversible electric motor mounted in said housing, a cord sheave rotatably mounted'in said housing about an axis perpendicular to the plane of said cord, gear means intercoupling said motor and said sheave for rotating the latter when said motor is powered, a pair of idler pulleys each rotatably mounted in said housing about axes parallel to the axis of said sheave, a pair of tensioning pulleys each rotatably mounted in said housing about axes parallel to the axis of said sheave, individual mounting means for each of said tensioning pulleys arranged to permit longitudinal motion of said tensioning pulleys toward and away from a respective one of said openings, each of said mounting means comprising a compression spring arranged to urge the corresponding tensioning pulley away from the corresponding opening, and a pair of stop arms each disposed in the longitudinal path of a respective one of said tensioning pulleys and arranged to limit longitudinal motion of the corresponding tensioning pulley toward the corresponding opening, said pulleys and said sheave being arranged so that said cord entering one of said openings may be threaded first around the corresponding tensioning pulley, thence around one of said idler pulleys, thence around said sheave, thence around the other idler pulley, thence around the other tensioning pulley and through the other opening, the strength of said springs being selected so that when said motor is powered the tensioning pulley corre sponding to the tensioned cord leg contacts the corresponding stop while the other tensioning pulley assumes an intermediate position in which the slack co-rd leg is maintained under at least some tension.

8. An operator as set forth in claim 7 in which said sheave is rotatable under manual torce applied to said operating cord and tending to rotate said sheave.

9. An operator as set forth in claim 7 comprising a fixed guard mounted on said housing inwardly of said sheave and said idler pulleys and arranged to prevent accidental unthreading of said cord and a movable guard mounted on said housing outwardly of said sheave and said idler pulleys and arranged in one position thereof to prevent accidental unthreading of said cord and in another position thereof to expose said idler pulleys and said sheave for threading of said cord.

. 10. A powered operator for operating draperies and the like by imparting axial motion to an operating cord, comprising a housing having a cover 'with openings adapted to accommodate respective legs of an operating cord, a mounting bracket adapted to be attached to a surface adjacent the path of travel of said cord and arranged to releasably support said housing, a reversible electric motor mounted in said housing, a cord sheave rotatably mounted in said housing about an axis perpendicular to the plane of said cord, gear means intercoupling said motor and said sheave for rotatingthe latter when said motor is powered, a pair of idler pulleys each rotatably mounted in said housing about axes parallel to the axis of said sheave, a pair of tensioning pulleys each rotatably mounted in said housing about axes parallel to the axis of said sheave, individual mounting means for each of said tensioning pulleys arranged to permit longitudinal motion of said tensioning pulleys toward and away from a respective one of said openings, each of said mounting means comprising a compression spring arranged to urge the corresponding tensioning pulley away from the corresponding opening, and a pair of stop arms each disposed in the longitudinal path of a respective one of said tensioning pulleys and arranged to limit longitudinal motion of the corresponding tensioning pulley toward the corresponding opening, said pulleys and said sheave being arranged so that said cord entering one of said openingsmay be threaded first around the corresponding tensioning pulley, thence around one of said idler pulleys, thence around said sheave, thence around the other idler pulley, thence around the other tensioning pulley and through the other opening, the strength of said springs being selected so that when said motor is powered the tensioning pulley corresponding to the tensioned cord leg contacts the corresponding stop while the other tensioning pulley assumes an intermediate position in which the slack cord leg is maintained under some tension, said mounting bracket being adjustable to permit changing the position of said housing in a direction to decrease slack in said slack oord'leg as saidcord becomes permanently elongated in service. e

References Cited in the file of this patent UNITED STATES PATENTS 2,788,481 Lui et a1. Apr. 9, 1957 2,830,808 Graber Apr. 15, 1958 2,894,405 Carlo July 14, 1959 2,987,121 Haws June 6, 1961 FOREIGN PATENTS 910,390 Germany May 13, 1954 

1. A POWERED OPERATOR FOR OPERATING DRAPERIES AND THE LIKE BY IMPARTING AXIAL MOTION TO AN OPERATING CORD, COMPRISING A REVERSIBLE MOTOR, A CORD SHEAVE, MECHANICAL MEANS INTERCOUPLING SAID MOTOR AND SAID SHEAVE FOR ROTATING SAID SHEAVE WHEN SAID MOTOR IS POWERED, A PAIR OF TENSIONING PULLEYS, MOUNTING MEANS FOR SAID TENSIONING PULLEYS ARRANGED TO PERMIT TRANSLATIONAL MOTION OF SAID TENSIONING PULLEYS, SAID SHEAVE AND SAID PULLEYS BEING ARRANGED SO THAT AN OPERATING CORD MAY BE THREADED AROUND ONE TENSIONING PULLEY, THENCE AROUND SAID SHEAVE AND THENCE AROUND THE OTHER TENSIONING PULLEY, WHEREBY ROTATION OF SAID SHEAVE IN ONE DIRECTION CAUSES SAID CORD TO ADVANCE AXIALLY IN ONE DIRECTION AND ROTATION OF SAID SHEAVE IN THE OTHER DIRECTION CAUSES SAID CHORD TO ADVANCE AXIALLY IN THE OTHER DIRECTION, BIASING MEANS OPERATIVELY COUPLED TO SAID TENSIONING PULLEYS AND CONSTANTLY URGING SAID TENSIONING PULLEYS TO MOVE IN A DIRECTION TO MAINTAIN SAID CORD IN TENSION, AND A STOP DISPOSED IN THE PATH OF MOTION OF EACH OF SAID TENSIONING PULLEYS AND ARRANGED TO LIMIT MOTION OF SAID TENSIONING PULLEYS IN A DIRECTION OPPOSITE TO THE DIRECTION OF MOTION RESULTING FROM URGING OF SAID BIASING MEANS. 